— Former businessman Herman Cain holds a narrow lead in South Carolina’s Republican primary, and he’s running neck and neck in Florida with former Massachusetts Gov. Mitt Romney, according to two new NBC News-Marist polls.

These two states have played pivotal roles in past Republican presidential nominating contests: Since 1980, the winner of South Carolina’s GOP primary has gone on to win the party’s nomination, while Florida ultimately decided the party’s pick in 2008. This cycle, South Carolina’s contest will occur on Jan. 21 and Florida’s will take place on Jan. 31.

“The road to the convention is going to go through these two states,” said Lee Miringoff, the director of Marist College’s Institute for Public Opinion.

Among a broader pool of Republicans in South Carolina, Cain is at 28 percent and Romney is at 27 percent.

In Florida (Download poll PDF), Cain is at 32 percent among likely voters, Romney at 31 percent, Perry at 8 percent and Paul and Gingrich are at 6 percent; 11 percent say they are undecided.

Among a broader range of Florida Republicans, Romney is at 30 percent and Cain is at 29 percent.

Breaking down the Cain vs. Romney divide What is particularly striking is the difference in support between Cain and Romney in both states. Cain performs better among Tea Party backers, very conservative voters, evangelical Christians and Republicans who have viewed the past GOP debates.

Romney, by contrast, over-performs among Republicans who don’t identify with the Tea Party, as well as those who consider themselves liberals and moderates.

“This is a very, very divided electorate,” said Barbara Carvalho, director of the Marist Poll.

And there’s also a divide in the level of support. In South Carolina, 45 percent of Cain’s supporters in South Carolina strongly back him, versus 37 percent of Romney’s. In Florida, 52 percent of Cain’s supporters strongly back him, versus 41 percent of Romney’s.

As in the recent NBC-Marist polls of Iowa and New Hampshire — which showed Romney leading both contests — likely Republican voters in both South Carolina and Florida place more emphasis on issues and values than on experience and electability.

In South Carolina, a combined 58 percent say a candidate sharing their values or their positions on the issues is more important in deciding their vote. That’s compared with a combined 39 percent who say experience and electability will determine their vote.

In Florida, it’s a combined 54 percent for values and issues, versus 44 percent for experience and electability.

Also in South Carolina, 53 percent of likely GOP voters don’t believe Mormons are Christians, or say they are unsure about it. Among those respondents, Cain leads Romney (who is Mormon), 33 percent to 19 percent — with Perry at 11 percent.

In Florida, just 42 percent of likely GOP voters don’t believe Mormons are Christians or are unsure.

Obama vs. the GOP field President Barack Obama’s approval rating in Florida — a key general-election state — stands at 41 percent, with 49 percent disapproving of his job performance.

In a hypothetical general-election match up in the Sunshine State, the president is up two points on Romney, 45 percent to 43 percent. He leads Cain by six points, 47 percent to 41 percent. And he’s ahead of Perry by eight points, 47 percent to 39 percent.

In South Carolina — a GOP stronghold in presidential contests — Obama’s job-approval rating stands at 40 percent, and he trails Romney, Cain and Perry in head-to-head match ups in the Palmetto State.